This is a revised re-submission of a competing renewal for a Program Project grant that focuses on pediatric affective disorders (depression and anxiety). These disorders are frequent, chronic, recurrent, and associated with significant morbidity, functional impairment, and mortality. In response to the previous review we have clarified issues raised by the IRG, provided additional information and descriptions regarding several areas of the studies, and have better delineated the inter-relatedness across the projects and cores. The four projects in the revised application will: (I) Study patterns of mood, cognition, behavior, sleep/activity patterns, social activities, media use and daily stressors in home environments in a new sample of PAD and control subjects before and during acute treatment; (2) Study the multi-year course of our large longitudinal sample of children and adolescents with PAD and controls as they enter young adulthood; (3) Use event related fMRI to examine reward-expectancy, experience of reward, experience of loss, and decision-making under varying reward contingencies to investigate the neurobehavioral systems involved in reward-anticipation, loss, and behavioral choice in PAD and control children; (4) Study mood, cognition, and behavior in the home in a sample of bipolar adolescents, characterizing day-to-day variability and changes in response to naturalistic treatment. Common themes through the work of these projects include: the neurobehavioral systems involved in positive and negative affect and approach/withdrawal behaviors; serotonergic systems, the importance of studying complex behavior in a natural setting; and the importance of understanding the longitudinal course of these interrelated disorders.